The present invention relates to a disposable aerosol bacterial contamination test apparatus for the reliable or measured collecting of air stream sample particulates on a bacteriological culture medium for the purpose of determining bacterial contamination of the air stream and/or its source equipment. The invention is herein illustratively described by reference to the presently preferred embodiment thereof; however it will be recognized that certain changes may be made therein with respect to details without departing from the essential features involved.
Residual contamination in hospital respiratory machines such as ventilators and anesthesia gas machines can communicate lung infections. Such machines normally employ water reservoirs and humidifying devices which function to deliver to the patient breathing gases containing moisture in the form of aerosol particles. The moist, warm environment provided in the breathing circuits of such machines provides ideal environment for the growth of various pathogenic organisms that can cause lung infections. Typical of these nosocomial respiratory infections is bacterial pneumonia.
Obviously, in addition to frequent antiseptic decontamination of medical ventilating equipment, a vigorous bacteriological surveillance program is essential, a program in which the equipment undergoes regular testing for the growth of pathogenic organisms. The sterilization, assembly and preparation of conventional reusable culturing equipment is, however, time-consuming and inconvenient for laboratory technicians. As a result, hospital programs for bacterial surveillance of ventilating equipment, commonly acknowledged as being essential for patient protection, are sometimes conducted less vigorously than prudence dictates.
A common method of testing equipment for bacterial growth is to take swab cultures. In this method, sampling is conducted by rubbing cotton swab sticks on various surfaces of the ventilating equipment, reservoirs, tubing, face masks and other components. The swabs are then smeared on the surface of a culture medium in a petri dish which is subsequently incubated for a period of time and then checked for bacterial growth. The swab method, however, only tests for surface contamination and may not reveal whether there is contamination in the aerosol gases that are delivered to the patient by the machine. As a result, the so-called aerosol sampling method is preferred over the swab technique. The aerosol method permits direct sampling of the aerosol effluent carried from the machine to the patient's respiratory tract, and thus provides a more reliable test.
Aerosol sampling is commonly conducted by sampling and incubation on a culture medium, such as agar, poured into a test tube where it is allowed to harden. In one technique a funnel is then placed loosely in the top of the test tube and the flexible feed tube from the ventilating machine placed against the funnel feeds effluent gas into the test tube. The effluent impinges on the culture medium which collects the particulates, and, then exhausts from the open end of the test tube around the funnel. While an attempt is made to regularize or standardize the rate at which particles are collected on the medium the pattern of flow in the test tube exposing the medium to the particles is variable because of varying placement of the funnel in the mouth of the test tube. This introduces a variable in the collection process that lends a degree of uncertainty in the quantitative aspects of the test. Moreover, as stated above, the inconveniences of preparing, assembling and using the disassociated components is also a deterrent to consistently diligent testing.
It is an object of the present invention, therefore, to provide a reliable, easy-to-use, inexpensive and disposable test kit which incorporates all of the functional features required for the performance of aerosol bacteriological sampling and subsequent incubation and examination processes.
A further object is to provide an aerosol test container device so formed as to induce a regularized and efficient columnar flow effluent gases against the collecting culture medium in the bottom thereof, by channeling the outflow of such gases away from the incident flow.
It is an additional object to provide a kit assembly in which the components are available and organized to facilitate performing each of the successive process steps in making a complete test.